This is the second competitive renewal of the Drosophila Genome Center. The major aim for the three years covered by this proposal is to complete the determination of the genomic sequence of the 12 Mb euchromatic portion of the Drosophila melanogaster genome. The biologically-annotated sequences of the genomes of the model organisms will provide an invaluable key to understanding the sequence of the human genome. An important goal of the Drosophila Genome Center is to facilitate this endeavor. To that end we proposed to develop a detailed genome-wide biological underpinning to the DNA sequence data as it emerges. Our work in this area has three components: (1) the use of P-element-mediated insertional mutagenesis to conduct a gene disruption experiment of unprecedented scale in a metazoan organism; (2) the study of expressed sequences through the characterization of the sequence and expression pattern of cDNA molecules; and (3) the development of informatics tools to support the experimental process, to identify features of the DNA sequence, and to allow the presentation of up-to-date information on the annotated sequence to the world-wide research community.